Download Production of Naked-Seeded Pumpkin: A Food Crop for the Family

Production of Naked-Seeded
Pumpkin: A Food Crop for the
Family Farm
R. G. Robinson
Miscellaneous Report 156-1981
UNIVERSITY OF MINNESOTA
AGRICULTURAL EXPERIMENT STATION
ST. PAUL, MN 55108
Production of Naked-Seeded Pumpkin:
A Food Crop for the Family Farm
Naked-seeded pumpkin is a new crop of potential
value for people who want to develop a lifestyle based
on natural foods and self-sufficient food production.
Most people like the taste of pumpkin seed, and the seed
contains more protein than needed for human nutrition. Consequently, it can supplement foods made from
grain crops that often lack sufficient protein for human
needs.
Naked-seeded pumpkin has been tested, intermittently, at Rosemount, Minnesota since 1964 as a potential oilseed crop, but its yield and production costs do
not justify commercial production for oil. However,
some varieties do warrant production for edible seed.
Pumpkin acreage for planting stock seed in the
United States totalled 302 acres in 1980, with an average yield of 529 pounds per acre. Most of this production
was not of naked-seeded varieties. Acreage grown for
confection or food seed is not known.
What Is Naked-Seeded Pumpkin?
Naked-seeded pumpkin (Cucurbita pepo L.) vari·
eties were developed from natural mutants whose integuments (seed coats) were very thin in contrast to the
thick, hard, and close-fitting integuments (hulls) of
normal pumpkin seed. Pumpkin hulls arc in close
contact with the meat (cotyledons and primary axis) of
the seed and cannot be removed efficiently by the
methods used for dchulling sunflower.
Sunflower hulls are the peri carp (ovary wall) and arc
attached to the true seed at only one point (funiculus).
Sunflower integuments, like those of pumpkin, closely
contact the cotyledons and remain on the dehulled
seed; therefore, dehulled sunflower seed and nakedseeded pumpkin seed arc morphologically equivalent.
Varieties
The naked-seeded variety, Lady Godiva, was released by the USDA in 1972. 1 The fruits weigh about 5
pounds and are yellow with green stripes at maturity,
but the green may continue to fade as senescence
proceeds. The flesh can be sliced and eaten raw like a
salad, but the flesh is of poor quality for cooking because
of its stringy texture and pale color. The seed is green
with very thin and loose integuments and is about three
times the size of a dehullcd sunflower seed. Test weight
per bushel is about 43 pounds.
The Triple Treat variety was released by the W.
Atlee Burpee Co. in 1977 and is used for jack-o-lanterns,
cooking, and naked seed. 2 The deep orange flesh is of
Author
R. G. Robinson is a professor in the Department of
Agronomy and Plant Genetics, University of Minnesota.
The Univt.:rsity of Minnesota, including the Agricultural Experiment
Station, is committed to the policy that all persons shall have equal
access to its programs, facilities, and employment without regard to
race, creed, color, sex, national origin, or handicap.
1lady
Godiva seed is available /rom W. At lee Burpee Co., Clinton, IA 527,12, and
Ceo. W. Park Seed Co., Inc., Greenwood, SC 29647.
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Triplc Treat seed is available from W. Atlcc Burpee Co., Clinton, IA 52732.
2
NORMAL EEO
NAKED
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OD IVA
TRI L TR AT
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1
e normal seed is from a retail packet of the "crack and spit" type. Lady Godiva and Triple Treat are naked-seeded varieties.
minimum amount of total protein must be consumed in
order to provide the required amounts of methionine
and cystine. Nonetheless, 0.33 to 0.44 pounds per day of
pumpkin seed or 0.43 to 0.58 pounds per day of sunflower seed supply recommended amounts of protein
and all essential amino acids for adults. These amounts
contain 828 to 1,104 and 1,092 to 1,473 calories, respectively, for pumpkin and sunflower.
Protein percentages of pumpkin and sunflower are
calculated by various methods. However, the methods
are calibrated to give protein percentages based on the
product of percent nitrogen times a nitrogen-to-protein
conversion factor. The factor commonly used for both
crops is 6.25, but the factor 5.3 has also been used.
Analyses of naked-seeded pumpkin seeds grown at
Rosemount and dehulled sunflower seeds grown at
Rosemount, Morris, Crookston, and Grand Rapids,
Minnesota indicate that nitrogen-to-protein conversion
factors were 6.10 for sunflower and 5.65 for pumpkin. 4
ng quality. However, unlike Lady Godiva,
integuments are noticeable when the seed is
re 1).
aker variety is reported suitable for jack-ooking, and naked seed. 3
Value and Chemical Composition
and sunflower seed have some similar
aracteristics, and both are potential food
mily farm. Data for seed of both crops are
hles 1to3. Naked-seeded pumpkin seed
wer meats in protein percentage and is a
urce of high quality protein (Tables 1, 2).
nflower seed proteins are high in globud both crops are similar in amino acid
e essential amino acids for human
ent in both crops, but more than the
~from
Burgess Seed & Plant Co., Bloomington, IL
o., Randolph, WI 53956; Nichols Garden Nursery,
4
3
Robinson, R. G. I975. Amino acid and elemental composition of sunflower and
pumpkin seeds. Agron. J. 67:541-544.
Table 1. Average nutritional composition of Lady Godiva pumpkin seed and dehulled nonoilseed sunflower
seed produced at Rosemount, Minnesota
Nutrient
Protein
Oil
Ash
Fiber
Carbohydrate
Pumpkin
-------------38.0
45.9
4.8
7.9
11.3
Table3. Averageele
pumpkin seed and d
produced at Rosemou
Sunflower
Element
percent 1
28.5
48.5
3.8
4.0
19.2
Nitrogen
Phosphorus
Potassium
Magnesium
Sulfur
Calcium
Sodium
'Dry-weight basis.
Iron
Zinc
Manganese
Aluminum
Boron
Copper
Molybdenum
Table 2. Average amino acid concentrations in Lady
Godiva pumpkin seed and dehulled nonoilseed sunflower seed produced at Rosemount, Minnesota
Amino acid
In seed
In seed protein
Pumpkin Sunflower Pumpkin Sunflower
Glutamic acid
Arginine
Aspartic acid
Leu cine
Phenylalanine
Valine
Alanine
Glycine
Serine
Isolcucine
Lysine
Tyrosine
Pro line
Histidine
Threonine
Methionine
Cystine
Tryptophan 1
------------------------ percent -----------------------5.19
4.76
18.30
21.74
4.59
2.20
16.17
10.08
2.56
2.20
9.02
10.04
2.16
1.53
7.58
7.00
1.54
1.16
5.43
5.29
1.49
1.21
5.25
5.51
1.32
1.02
4.63
4.67
1.29
1.18
4.54
5.39
1.19
0.87
4.19
3.99
1.15
0.99
4.05
4.49
0.85
4.01
3.93
1.14
1.09
0. 70
3.84
3.24
0.92
0.81
3.21
3.68
0. 76
0.62
2.68
2.81
0. 71
0.83
2.49
3. 79
0.65
0.50
2.27
2.30
0.10
0.11
0.37
0.40
0.56
0.34
1.98
1.59
ally. Common diets c
consumption of these
sodium ratio closer to
Pumpkin is adapted
has performed well on
on irrigated and dryland
might be a problem in nQ
lings are sensitive to frost
slowly in cold soil. Pla
resulted in rapid emer
the seed to mature bef
The first frosts in the £
but the stems and prote
and maturation procee
Naked-seeded pump
mination and produces
the fragmentary seed .co
rotting in the soil. The
planting in warm soil a
treatment. The seedlings
stage inside and then t
ever, direct field plant'
desired population foll
more practical than tra
were occasionally obtaine
treatment was usually ne
1
Tryptophan data are adapted from Orr, M. L. and B. K. Watt. 1957. Amino acid
content of foods. USDA Home Economics Research Report 4: 1-82.
Both pumpkin and dehulled nonoilseed sunflower
seed contained less than 50 percent oil (Table 1), but the
sunflower oil is nearly 90 percent unsaturated compared with pumpkin oil of nearly 80 percent unsaturation. Minnesota sunflower oil is about 68 percent polyunsaturated (linoleic acid), whereas pumpkin oil is
about 42 percent linoleic acid. Although sunflower oil is
preferred, both oils have a satisfactory fatty acid composition for an edible oil.
The integuments contain much of the fiber in pumpkin and sunflower seeds. The integuments are not
noticeable when sunflower seed is consumed, but they
continually flake off of naked-seeded pumpkin seed.
Because of this, consumption of fiber would be less than
the 7.9 percent indicated in Table 1. Fiber is needed to
regulate bowels, and seed fiber is desirable in a normal
human diet.
Seeds of both crops are adequate sources of all
minerals likely to be deficient in human diets except
calcium (Table 3). An adult male must eat 4.4 pounds of
pumpkin seed or 1. 76 pounds of sunflower seed to get
enough calcium. The phosphorus-calcium ratios also
differ greatly from the desired 1 to 1. The high potassium-sodium ratio in these seeds is desirable nutrition-
63
74
26
2
6
25
6
sodium, so
potassium!.
inate very
20andJune 5
pletime for
in September.
opy of leaves,
sually escape
y of high gergs. However,
.the seed from
is reduced by
ngicidal seed
he cotyledon
field. Howe times the
is generally
actory stands
ted seed, but
e 4). Germina-
Table 4. Planting depth an
untreated naked-seeded p
Depth
(inches)
1
4
Field
l
so
2
3
4
5
38
20
17
32
Captan fungicide.
tion is rapid if the seed is planted in moist soiL The
hypocotyl elongates and the cotyledons attached at the
first node emerge about 7 days after planting. The
hypocotyl is capable of elongating more than 6 inches,
but deep planting delays emergence. A planting depth of
1 to 2 inches is optimum (Table 4). Flowers appear about
1 month after emergence and flowering continues for
the rest of the summer.
Plant Population and Its Arrangement
Lady Godiva pumpkin produces long, prostrate runners about 10 feet long but many extend to 20 feet.
Consequently, choice of row spacing does not limit
final ground cover. A plant population of 10,454 plants
per acre in a 30-inch x 20-inch arrangement gave highest
yield, and I, 742 plants per acre in a 60-inch x 60-inch
arrangement gave lowest yields at Rosemount (Table 5).
The USDA in Beltsville, Maryland, reported higher
yields from 10,890 plants per acre in a 24-ineh x 24-inch
arrangement than from 1,210 plants per acre in a 72inch x 72-inch arrangement.
The rind and flesh remaining after seeds are removed
are about 90 percent water, so the first treatment in
Table 5 produced 1,185 pounds of seed and about 2 tons
(dry weight) of fruit residue for hog or cattle feed. The
residues remaining after seed removal arc about I
percent protein and l 1/2 percent fiber on a wet basis or
about 12 percent protein and IS percent fiber on a dry
weight basis. The flesh of varieties of good cooking
quality can be used for human food.
Figure 2. Plants at this stage can be cultivated.
noticeably injure naked-seeded pumpkin and controlled
annual grass and most dicot weeds in plots at RoseInount.
Botanical Relationships and Seed Maintenance
Pumpkin belongs to the Cucurbita genus of the
Cucurbitaceae family of plants. This genus includes
four annual species. All arc monoecious (male and
female flowers are borne separately on the same plant)
and require bees to transfer pollen. Cucurbita fruits are
a type of berry called a pepo. The outer layer of the pepo
is receptacle tissue covering the ovary. In turban types,
the receptacle does not completely cover the ovary, and
the pericarp is exposed.
The common groups of Cucurbita arc not separated
on the basis of botanical species as shown by the
following classification.
Cucurbita pepo L. includes naked-seeded pumpkin,
Connecticut Field, Jack-0-Lantern, Spirit, Spookie,
Young's Beauty, Early Sugar, and Small Sugar pumpkin,
Zucchini, Scallop, Patty Pan, Crookneck, Cocozclle,
Straightneck, and Vegetable Marrow summer squash,
Acorn, Table Queen, and spaghetti winter squash, and
most ornamental gourds. Cucurbita maxima Ouch.
includes Big Max and Mammoth (Chili) pumpkin; Hubbard, Banana, Delicious, Boston Marrow, Buttercup,
Kitchenette, Greengold, Turban, and Rainbow winter
Weed Control
Good weed control is needed before the runners
extend between the rows and prevent close cultivation
(Figure 2). The tall, dense growth of leaves from the
prostrate runners kills late emerging weeds. But earlyemerging weeds in the row and those missed by the
cultivator may be too tall for the pumpkin vines to
control by shading.
Herbicides approved for pumpkin, but probably not
tested on naked-seeded varieties, include chloramben
(Amiben) at 3 to 4 pounds per acre preemergence or
preplan! incorporated and dinoseb amine (Premerge,
Dinitro Weed Killer) at 3 to 6 pounds per acre preemcrgence. Dinoseb should not be used in sandy soil, and
pumpkin seed should be planted at least I inch deep.
Chloramben at 3 pounds per acre preemergence did not
Table 5. Plant population-plant arrangement effects on yield of Lady Godiva pumpkin at Rosemount; 1974, 1976,
1980 averages.
Plant
Plants/acre
10,454
5,227
5,227
1,742 1
arrangement
(inches)
30x20
60x20
60x60
60x60
(3/hill)
LSD 5%
1
Seed yield-dry
per fruit
(ounces)
(pounds)
per acre
1.6
1.7
1.8
1.7
1,185
825
904
774
228
1-year data adjusted to be comparable with 3-year data.
5
per acre
(pounds)
52,000
37,000
45,000
42,000
13,000
Fruit yield-wet
per acre
(number)
11,572
7,542
8,015
7,277
2,138
per fruit
(pounds)
4.6
5.0
5.7
6.0
-
I
Figure 3. Fruits ~pcpos) of four varieties of Cucmbita. The two fruits at the left arc buttercup winter squash C. maxima. The next three fmits arc
C. pepo varicth.:s-spaghctti winter squash, Triple Treat naked-seeded pumpkin, and Lady Godiva naked-seeded pumpkin.
squash. Cucurbita moschata Ouch. includes Kentucky
Field, Dickinson, Cheese, and Cangold pumpkin; Butternut and Alagold winter squash. Cucurbita mixta
Pang. includes Cushaw and Tennessee Sweet Potato
pumpkin and Silvcrsced gourd.
Extreme variation within species of Ctzcurbita
makes identification of species difficult. The stems and
peduncles !fruit stem) of C. pepo, moschata, and mixta
arc generally hard and angular whereas the stems and
peduncles of C. maxima are soft and round !Figure 3).
However, the peduncles of C. maxima are enlarged by
soft, corky tissue and those of C. mixta by hard, corky
tissue. The peduncles of C. moschata flare out at their
attachment with the fruit. Leaves of C. maxima are
more rounded in outline and either not lobed or only
faintly lobed compared to the other three species.
The naked-seeded pumpkin varieties will intercross
with all annual Cucurbita species and varieties except
Cucurbita maxima. Therefore, isolation is needed to
prevent loss of the naked-seeded characteristic in subsequent generations. At Rosemount, '14 mile isolation was
not enough but 1 mile was sufficient to maintain pure
seed. Naked-seeded pumpkin seed retains its viability
for several years if kept dry in storage. Growers who
wish to raise other varieties of Ctzctzrbita could produce
planting seed in an isolated plot or grow only varieties of
Ct1curbita maxima near Lady Godiva the year that
planting seed is desired. No isolation is needed if the
seed will be used for food. However, a few plants of
naked-seeded pumpkin surrounded by other species of
Cucurbita may produce some fruits without seed because of the parthenocarpic effect of foreign pollen.
Some commercial seed producers may use vine crop
harvesters to pick and thresh pumpkin in the field. The
seeds and pulp are separated by washing and then dried.
Seed may also be a by-product of commercial canning.
Seeds may be removed by cutting the fruit in half
and scooping them out by hand or with a metal scraper.
Or the fruit can be broken by slamming it against a
pavement. Three double rows of seed are attached
around the central cavity making hand stripping fairly
efficient. The pulp and seeds are wet and slippery, but
they can be separated by flushing with water through a
container with a coarse mesh bottom. The seeds can be
dried in thin layers on a screen, in a farm d1yer, or in an
oven. Low temperature drying is necessary if the seed is
intended for planting.
The seed can be eaten raw, roasted dry, or roasted in
oil. When dry roasted at about 350°F, the seeds make a
popping noise and swell but don't invert like popcorn. A
different flavor is achieved by lightly coating the seeds
with oil before roasting. Roasting in an oven takes about
15 minutes. In a fry pan on top of the stove, the seed will
bum in just a few minutes and must be covered to
prevent the popping seeds from escaping.
Summary
Naked-seeded pumpkin is a "natural food" crop that
produces about 1,000 pounds of edible, high-protein
seed per acre. Pumpkin seed and sunflower seed have
many nutritional similarities, but they are complementary in taste and texture. Both are staple foods that will
supplement other foods that lack sufficient protein for
good nutrition.
Naked-seeded pumpkin is also a potential oilseed
and high-protein seed crop, but current varieties
and production costs do not warrant commercial
production.
Harvest and Preparation for Food
The seeds mature in September but the fruits are
usually harvested in October after killing frosts. Lady
Godiva fruits arc yellow with green stripes; those of
Triple Treat and Streaker are orange.
6